Apparatus for assembling veneer into plywood sheets

ABSTRACT

Apparatus for assembling veneer into plywood sheets is disclosed. Two sources of veneer, one above the other, are adjacent an assembly station. The assembly station has a lift table to receive the veneer for assembly. An interrupted slat conveyor takes, alternately, two sheets of veneer from the top source of veneer, and one sheet from the bottom source of veneer. The veneer on the conveyor engages a stop above the lift table to drop between the slats of the conveyor onto the lift table as the slats of the conveyor move out from under the veneer. After each deposit of veneer on the lift table, core pieces are taken from gluing rolls and laid on the deposited veneer, the end core sheet being supported by a retractable support member.

United States Patent [72] Inventors Ronald .I. Billett Sunnyvale;

Veikko K. Viitanen, San Jose, both of,

Calif. [21] Appl. No. 813,812 [22] Filed Apr. 1,1969 [45] Patented Aug. 10, 1971 [73] Assignee FMC Corporation San Jose, Calif.

{54] APPARATUS FOR ASSEMBLING VENEER lNTO PLYWOOD SHEETS 3 Claims, 12 Drawing Figs. [52] US. CL... 214/6 UK [51] int. Cl 865g 57/06 [50] Field Search 214/6 K, 6 M; 271/68, 75, 76 [56] References Cited UNITED STATES PATENTS 3,028,979 4/1962 Zachow 214/6 (K) 3,346,128 10/1967 Hullhorst 21416 (K) Primary ExaminerGerald M. Forlenza Assistant Examiner-George F. Abraham AttorneysF. W. Anderson and C. E. Tripp ABSTRACT: Apparatus for assembling veneer into plywood sheets is disclosed. Two sources of veneer, one above the other, are adjacent an assembly station. The assembly station has a lift table to receive the veneer for assembly. An interrupted slat conveyor takes, alternately, two sheets of veneer from thetop source of veneer, and one sheet from the bottom ,J source of veneer. The veneer on the conveyor engages a stop above the lift table to drop between the slats of the conveyor 1 onto the lift table as the slats of the conveyor move out from under the veneer. After each deposit of veneer on the lift table, core pieces are taken from gluing rolls and laid on the deposited veneer, the end core sheet being supported by a retractable support member.

PATENTEI] AUBIOIQYI 3,598,252

SHEET 1 0F 5 I E'IE1'| 1 AT TORNE YS PATENTED AUG] 0 I97} QM k SHEET 3 BF 5 F'IE E PATENTED AUG] 01971 SHEET '4 OF 5 APPARATUS FOR ASSEMBLING VENEER INTO PLYWOOD SHEETS BACKGROUND OF THE INVENTION The present invention relates to apparatus for assembling veneer into plywood sheets.

Generally, plywood is assembled into panels manually from veneer and glued core strips, the latter of which are sandwiched between the veneer to join the veneer into plywood sheet. Normally, four operators are used to assemble each sheet: two operators to place veneer at an assembly station, one operator to pass core strips through a gluing machine, and one operator to take the glued core strips from the gluing machine and place them on the veneer. If, for example, five ply panels of plywood are being assembled, the first, third and fifth ply will be veneer;-the second and fourth ply will be glued core strips. In the usual case, different-quality veneer is used for different layers. Conventionally, the veneer handlers will bring the face veneer of one sheet and the back veneer of the next sheet together in stacked relation to the assembly station, since no glued core strips are required therebetween. The middle veneer is brought alone to the assembly station.

Efforts have been made to automate the plywood assembly process, but, ingeneral, the mechanisms developed have been quite complicated and expensive. It will be appreciated that excessive complexity or high cost of the mechanism can render the device impractical or economically infeasible.

SUMMARY OF THE INVENTION In the present invention, simple, effective mechanism is provided for assembling plywood sheets in which the veneer is brought automatically into the assembly station to eliminate the tiring and costly manual transport of the veneer thereto. In brief, in the preferred form of the invention, the veneer is supplied from two sources adjacent the assembly stationv These sources may, for example, be two roller conveyors, one above the other. For purposes of illustrating the mechanism of the present invention, it will be assumed that the face and back veneer for a five-ply plywood sheet are delivered together from the top roller conveyor, and that the middle veneer for the sheet is delivered from the lower roller conveyor.

. In the preferred form of the present invention, an endless conveyor encircles a conventional lift table in the assembly station, the upper run of the conveyor passing above the lift table and the lower run passing beneath the lift table. The conveyor has groups of slats to support veneer, the groups being spaced apart to'permit veneer to drop between the groups. In the assembly of plywood sheets, intermediate core strips are fed through a glue machine to the operator who lays them on the back veneer, as in the conventional manual assembly. However, a movable shelf is provided to support the end core strip until it is covered by a veneer sheet. A single piece of middle veneer is then released from the bottom roller conveyor to the veneer-supporting portion of the interrupted slat conveyor. The conveyor carries the middle veneer into the assembly station and over the lift table therein. Although the conveyor continues to circle the lift table, the veneer engages a stop over the end-of the'lift table for discharge from the conveyor between the groups of slats onto the glued core pieces on the "lift table.

Thereafter, a second layer of glued core pieces is laid on the middle veneer. At this time, the two veneer layers from the upper roller conveyor are released as a unit to the interrupted slat conveyor. The two layers are discharged from the conveyor (the face veneer for the plywood sheet below back veneer for the next plywood sheet). As the two layers drop on the glued cores at the assembly station, a plywood sheet is completed and the back veneer for the next plywood sheet is ready in the'assembly station to receive the glued core strips.

It is, therefore,-one object of the present invention to provide simple, effective,mechanism for the assembly of plywood sheets. It is another object of the presentinvention to provide a conveyor for automatically carrying veneer into an assembly station in a plywood assembly machine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in perspective of a plywood assembly station incorporating the apparatus of the present invention;

FIG. 2 is a side view showing the interrupted slat conveyor in the assembly station;

FIG. 3 is a view of a plywood sheet as assembled in the assembly station, with layers broken away for clarity;

FIG. 4 is a view in cross section of a slat of the slat conveyor;

FIG. 5 is a view taken on the line 5-5 of FIG. 4;

FIG. 6 is a side view of the stops which hold veneer on the supply conveyors, and the operating mechanism therefor;

FIGS. 7 to 12 show the sequential operation of the slat conveyor as it takes veneer from the supply conveyors and deposits it on the stack of plywood sheets for assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT There is shown in FIGS. I and 2 apparatus for assembling plywood sheets PS shown in FIG. 3 from veneer and intermediate core strips. Two stacked conveyors constitute two sources SI and S2 for the veneer: the top conveyor S1 supplying the top, or face veneer I5 and the bottom, or back, veneer, l6; and the bottom conveyor S2 supplying the middle sheet of veneer 17. As in conventional assembly of five-ply plywood, the intermediate layers between the face and middle veneer, and between the middle and back veneer, is made up of core strips I8 laid across the veneer as shown in FIG. 3'. As in the typical assembly of plywood, the face and back veneer, (with the face sheet, which completes the previous sheet of plywood, on the bottom) .are supplied together to the assembly station AS. Core strips I8 are fed through the rolls I9, 20 ofa conventional glue-applying machine 21, and the glued strips which emerge from the rolls are laid on the back sheet by the operator. A sheet of middle veneer I7 is laid on the core strips and a second layer of glued core strips is laid on the sheet of middle veneer. Thereafter, another back and face sheet are together supplied to the assembly station with the face sheet down to lay on the second layer of glued core strips.

The apparatus of the present invention facilitates handling of the veneer in the assembly station and permits one man, in addition to the man feeding core strips through the gluing machine, to assembly the plywood sheets.

A platform 23 is provided for theoperator at the assembly station. A lift table, or elevator, 25, of the type shown in the U.S. Pat. No. 3,l l0,476 to W. A. Farris issued Nov. 12 1963, is mounted on the frame 24 of the assembling apparatus in the assembly station. A plurality of rotatable rollers 26 are mounted on the table, two of which 260 and 26b are power driven, through chains 27, 28, by motor 29. Discharge conveyor sections 30, 3I, having rollers 32, are mounted on the frame in a fixed position with the rollers 32 thereof level with the rollers 26 of the lift table when the lift table is in its lowermost position. The conveyor sections 30, 31 are spaced apart to define a gap therebetween.

After a stack 33 of plywood sheets has been assembled, motor 29 is energized to advance the stack off the lift table 25 and onto the discharge conveyor sections 30, 3! for removal from the assembly station.

The frame 24 has an upper shaft 35 journaled therein in front of the table. Two stub shafts 36a and 36b are journaled in the frame behind the table, one on'each side of the frame. The stub shafts do not extend inwardly as far as the lift table, and thus permit unobstructed removal of a stack 33 of plywood from the assembly station. Two lower shafts 37, 38,

in front of and behind the table, respectively, are also journaled in the frame. Each shaft 35, 37, 38 has two spaced apart sprockets 3,9. The two sprockets are fixed to each shaft on eitherside of the table. Stub shaft 361: has a sprocket 39 secured thereon on one side of the table aligned with the other sprockets on that side of the table. Stub shaft 36b has a sprocket 39 secured thereon aligned with the sprockets on the opposite side of the table. An endless chain 40 is mounted on the four sprockets 39 on one side of the table, and a similar chain 41 is mounted on the four sprockets 39 on the opposite side of the table.

Groups 50 of cross slats l span the chains 40, 41. Each slat comprises a crossbar 52 terminating in short legs 53, 54 perpendicular to the crossbar at each end. The legs 53 of each slat are connected to chain 40 and the legs 54 are connected to chain 41 so that the crossbars 52 are are outside the closed path of the endless chains. Some of the slats have upstanding,

laterally sloping, guide pins 55 at one end adjacent the legs 54 the pins extending outwardly from the slats to guide veneer received thereon. The chains and spaced apart groups 50 of cross slats define an interrupted conveyor 56 to transport veneer into the assembly station. The leading slat has two upstanding stops 57 for engagement by the leading edge of the veneer to stop the veneer on the slats. The leading slat also has a ledge 58 thereon (see FIG. 7) to prevent the leading edge of a veneer sheet received thereon from lodging under the leading slat. The trailing slat has a ledge 59 (FIG. 7) to ease the leading edge of the veneer off the group of slats when the veneer is dislodged therefrom.

It will be noted that there are two groups 50 of slats, each group extending along the endless chains 40, 41 a distance slightly less than the length of a piece of veneer. The two groups 50 are spaced apart a distance slightly greater than the length of a piece of veneer. Thus the slats of the conveyor are interrupted for a span, or gap 60, sufficiently great to allow a piece of veneer to drop through the conveyor 56 onto the stack of plywood 33 on the lift table.

The interrupted endless conveyor 56 circulates continuously in the assembly station (except when stopped by release of footswitch 90 as hereinafter described) and encircles the lift table therein, the upper run of the conveyor passing over the table and the lower run passing under the table. The slats, as they pass around the end of the table, pass through the gap between the sections 30, 31 of the discharge conveyor.

Mounted on a bracket 62 connected to the frame adjacent the upper rear stub shafts 36a, 36b of the conveyor is a pneumatic actuator 63. The actuator 63 can be selectively extended and retracted by solenoid operated valve 63V, which is operated by switch 638. At the outer end of the actuator rod 64, there is a fixed stop 65 and a hinged stop 66. Also adjacent the stub shafts 36a, 36b, is another pneumatic actuator 70 (FIG. 2) pivotally connected to the frame. The actuator rod 71 can be selectively extended and retracted by solenoid valve 70V which is operated by switch 708. The rod 71 is pivotally connected to one of two levers 72 pivotally connected to the frame. Levers 72, at their upper ends have a support member 73 with extending fingers 74 (see FIG. 9) which defines a shelf.

During the plywood assembly operation, the interrupted conveyor 56 is driven by a drive unit 75 which is connected to and rotates shaft 38. The drive unit 75, which includes an electric motor, 75a, is controlled by a foot switch 90. The conveyor S1 receives a pair of veneer sheets, one pair at a time, and the conveyor S2 receives a single veneer sheet, one sheet at a time, from any suitable apparatus, such as that shown in the eopending application of Billett, Chamberlin, and McGee entitled APPARATUS FOR FEEDING VENEER TO PLYWOOD ASSEMBLY STATION (SJ 4795), Ser. No. 81 1,929, filed Apr. 1, 1969, assigned to the same assignee as the present invention. The pair of veneer sheets received on the conveyor S1 comprises a face sheet on the bottom and a back sheet 16 on top. The single sheet of veneer received on conveyor S2 comprises a sheet of middle veneer 17. The rollers 80 of conveyors S1 and S2 are continuously driven by belts 81 to urge the veneer forwardly in the direction indicated by arrow A. The pair of veneer on conveyor SI will be dispensed therefrom when gate 82 (FIG. 6) is flipped down by actuator 83. Actuator 83 is operated by solenoid valve 83V which is controlled by switch 838. The single sheet of veneer on conveyor S2 will be dispensed therefrom when gate 85 is flipped down by actuator 86. Actuator 86 is operated by solenoid valve 86V which is controlled by switch 86S.

As shown in FIG. 7, a pair of veneer sheets is released from conveyor S1 as the leading slat 51 of a group 50 of slats reaches the downstream end of the conveyors S1, S2. The pair of veneer sheets, which leave the conveyor S1 at a rate exceeding the rate of movement of conveyor 56, engage stops 57 connected to the leading slat. The veneer engages the guide pins 55 as it moves onto the conveyor 56 for accurate positioning thereon. At this time, a partially assembled plywood sheet, lacking only the face sheet, is resting on the stack of completed plywood sheets on the lift table, with glued core strips 18 exposed.

As shown in FIG. 8, as the conveyor 56 advances, the pair of veneer sheets are carried over the stack of plywood sheets, previously assembled, which have accumulated on the lift table. The partially assembled plywood sheet rests on top of the stack.

When the pair of veneer sheets reach the end of the upper run of the conveyor 56, the rod 64 of actuator 63 is in the extended position and the leading edges of the veneer pass under the hinged stop 66 to strike the fixed stop 65, as shown in FIG. 9. The hinged stop prevents the sheets from springing back from the fixed stop.

Although the veneer sheets are stopped, the conveyor 56 continues to move, as shown in FIG. 10, stripping the veneer off the group 50 of slats 51. As the slats move out from under the trailing edge of the veneer sheets, the rear ends of the sheets settle onto the glued cores.

After the group 50 of slats is completely out from under the veneer sheets, as shown in FIG. 11, the previous plywood sheet will be completely assembled, ready for the press, and the back sheet 16 of the next plywood sheet will be on top of the stack of completed sheets.

At this time, core strips are fed through the gluing machine and are laid on the back sheet 16 as shown in FIG. 12. As shown in FIG. 8, the support member, or shelf, 73 is in the advance position at this time with the fingers 74 thereof adjacent the stack 33 of plywood on the lift table. When the core strips are laid, the fingers 74 will support the final core strip if it overhangs thesheet being assembled. When all the core strips have been laid, gate 85 is dropped by actuation of actuator 86 by means of switch 868 to dispense a sheet of middle veneer. The middle veneer is moved over the stack by conveyor 56 and stripped therefrom in the same manner as the pair of veneer sheets 15 and 16. Actuator 70 is then operated by switch 70S to retract the support fingers 74.

A photoelectric cell PC mounted in frame 24 is provided to start the elevator motor (not shown) and lower the lift table 25 when the top veneer interrupts the light striking the cell. The table is lowered only until the cell again is struck by the light so that the top of the stack 33 is maintained adjacent the upper run of the conveyor. The upper limit of the elevator is defined by its position when the finger 91 thereon operates limit switch ILS. The lower limit of the elevator is defined by its position when the finger operates limit switch 2LS. When the lift table, or elevator, is loaded with plywood and reaches its lowermost position, motor 29 is energized to move the stack 33 onto conveyors 30 and 31. Thereafter, the lift table is raised to its uppermost position to begin receiving veneer for assembly of the next stack of plywood panels. It should be noted that the slat conveyor can be jogged by the operator at the assembly station. To utilize the jogging technique, the cores are fed through the rolls 19 and 20 of the gluing machine from left to right, as viewed in FIG. 1, so that the core strips nearest sources S1, S2 are supplied first. The operator then lays the glued core strips from left to right, jogging the conveyor 56 which is carrying the next sheet of veneer, as he progresses with the core laying. By the time the last core is laid, the next sheet of veneer will be close to stop 65 so that, in very little time, the next sheet of veneer can be laid on the glued core strips.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What we claim is:

l. Plywood-assembling apparatus at an assembly station comprising in combination a lift table having a vertically movable surface to receive veneer and support the veneer for assembly into plywood sheets, means to sense the. vertical position of the top sheet of veneer on said surface, means to adjust the vertical position of said table in response to said sensing means to maintain the top sheet of veneer at substantially a constant height, a stop mounted in the station, an interrupted conveyor movable along a path over said lift table surface to bring veneer against said stop, said conveyor having endless flexible side members below the top sheet of veneer on the lift table and having slats connected between said side members to extend across the conveyor, said slats having portions elevated above said side members to clear the veneer on the table and positioned along said side members in groups to define gaps between the groups at least as long as the'veneer, the veneer on said elevated slats dropping through said gaps on engagement with said stop, two stacked conveyors to feed veneer to said interrupted conveyor, and a discharge conveyor extending between said flexible side members to receive plywood sheets from the vertically movable surface of the lift table when said surface is in a lowered position, said discharge I conveyor having a gap to permit passage of the group of slats' on the interrupted conveyor.

2. An interrupted conveyor for transporting veneer to and depositing veneer on a table in a plywood sheet assembly station comprising a pair of flexible side members having a run group the surface of the top sheet of veneer on said table, a plurality of crossmembers connected between said side members in groups to define gaps between said groups, said crossmembers having center portions elevated above the top veneer on said table for clearance whereby a sheet of veneer can be deposited from said crossmembers onto the veneer on said table and the top sheet of veneer will be accessible to an operator without interference from a side member when said gap is in registration with the veneer on the table.

3. An interrupted conveyor for transporting veneer to and depositing veneer on a table having a vertically adjustable upper surface and having means to maintain the height of veneer on said surface substantially constant, said conveyor comprising a spaced pair of endless side chainsfmeans to mount said endless chains to position the upper run thereof below the top of the veneer on the table, a plurality of crossbars connected between said side chains in groups to define gaps between said groups, said crossbars having portions elevated with respect to the chains for clearance with the veneer on the table whereby a sheet of veneer can be deposited from said crossbars through said gaps onto the veneer on said table and the top sheet of veneer will be accessible to an operator without interference from the side chains when a gap in the groups of crossbars is over the veneer on the table.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated August 10, 122;

RONALD J. BILLETT et 31 Patent No. 3,598,252

Inventor-(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

I Column 2, line 46, change "assembly to assemble Column 3, line 10, delete "are" (second occurrence).

Column 6, line 4, change "group" to below Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.F'LETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. Plywood-assembling apparatus at an assembly station comprising in combination a lift table having a vertically movable surface to receive veneer and support the veneer for assembly into plywood sheets, means to sense the vertical position of the top sheet of veneer on said surface, means to adjust the vertical position of said table in response to said sensing means to maintain the top sheet of veneer at substantially a constant height, a stop mounted in the station, an interrupted conveyor movable along a path over said lift table surface to bring veneer against said stop, said conveyor having endless flexible side members below the top sheet of veneer on the lift table and having slats connected between said side members to extend across the conveyor, said slats having portions elevated above said side members to clear the veneer on the table and positioned along said side members in groups to define gaps between the groups at least as long as the veneer, the veneer on said elevated slats dropping through said gaps on engagement with said stop, two stacked conveyors to feed veneer to said interrupted conveyor, and a discharge conveyor extending between said flexible side members to receive plywood sheets from the vertically movable surface of the lift table when said surface is in a lowered position, said discharge conveyor having a gap to permit passage of the group of slats on the interrupted conveyor.
 2. An interrupted conveyor for transporting veneer to aNd depositing veneer on a table in a plywood sheet assembly station comprising a pair of flexible side members having a run group the surface of the top sheet of veneer on said table, a plurality of crossmembers connected between said side members in groups to define gaps between said groups, said crossmembers having center portions elevated above the top veneer on said table for clearance whereby a sheet of veneer can be deposited from said crossmembers onto the veneer on said table and the top sheet of veneer will be accessible to an operator without interference from a side member when said gap is in registration with the veneer on the table.
 3. An interrupted conveyor for transporting veneer to and depositing veneer on a table having a vertically adjustable upper surface and having means to maintain the height of veneer on said surface substantially constant, said conveyor comprising a spaced pair of endless side chains, means to mount said endless chains to position the upper run thereof below the top of the veneer on the table, a plurality of crossbars connected between said side chains in groups to define gaps between said groups, said crossbars having portions elevated with respect to the chains for clearance with the veneer on the table whereby a sheet of veneer can be deposited from said crossbars through said gaps onto the veneer on said table and the top sheet of veneer will be accessible to an operator without interference from the side chains when a gap in the groups of crossbars is over the veneer on the table. 